added the ability to hide the mask (e.g. if we want to format a credit card number as it is entered but not show ____ ____ ____ ____ before it is entered)
added displayMask setting to configure said behavior
fixed a bug that caused ? as the initial partial from causing the wrong return value from checking the mask
fixed an off-by-one error when positioning the caret upon focus of a partially filled field (when autoclear is off)